This invention relates to quick release mechanisms, and more specifically to adaptor collars used to releasably secure a tool at the end of a handle or shaft that can operate reliably in a vibratory and hot environment.
Such a mechanism is used in glass container molding machines to mount on a plunger shaft, a generally bottle-shaped form used to penetrate a molten glass ingot and pre-shape it into a parison, which is then inflated into a mold cavity. The surface deterioration imposed upon the form by the repeated impact on the molten glass requires its frequent replacement. That replacement must be accomplished quickly in order to minimize the interruption of the chain manufacturing pace of the apparatus. Furthermore, the form must be replaced while it still remains a very high degree of temperature.
A split adaptor collar has been used to secure the form on its supporting shaft. The two halves of the collar encircle the grooved head of the shaft and the grooved base of the form. The two halves are usually held in place by friction without any need for any type of complex or hard-to-manipulate fastener. This type of mechanism allows quick dismounting for the form with minimum manipulation.
However, due to the relatively unsecured and unstable mounting, the two halves of the collar tend to separate during the thrusting movement of the form into the molten glass ingot, and to rub against the walls of the surrounding guiding cylinder. Due to this abrasive action, small metal particles split away from the cylinder wall and penetrate the molten glass causing weakness points in some of the glass containers.
In some later devices the split collar which was used to secure the plunger to the head of the shaft has been replaced by a solid collar or sleeve as disclosed in U.S. Pat. No. 4,636,240 Kozora. A spring-biased bayonet-type interconnection between the sleeve and the plunger, allows for quick removal and replacement of the plunger. The sleeve itself is secured to the head of the shaft by screws. However, the intense shocks and vibrations to which such an assembly is subjected during parison-forming operations tends to overcome the spring pressure which locks the bayonet connector, and to loosen the screws that secure the sleeve to the shaft. None of the prior art securing devices known to the inventor is able to reliably prevent spontaneous disengagement of the plunger in such a demanding environment. Other pin devices that secure collars to shafts etc., and cited as prior art e.g. Davis ('998), Caquellin et al ('815), Fedderson et al ('778), Jamison ('658) and Davis ('191) rely purely on spring bias means of retention. Thus far locking devices that depend entirely on spring retention for engagement have not proved to withstand the severe operating conditions, that these particular collars are subjected to in the harsh environment peculiar to the glass industry.
In some of the above cited prior arts, external tools or manual manipulation must be employed for disengaging the pins. The prevailing limited access in a hot enclosure renders these approaches unworkable.
Because of the fact that no satisfactory mechanism thus far has proved to operate reliably in the severe environmental conditions that exist, there is a very real need for a more efficient and reliable mechanism between the components of parison-forming plunger assemblies in the glass industry.